Question

An electron is moving with a kinetic energy of $4.55\times {10}^{-25}$J. The de-Broglie wavelength for it (in ${10}^{-7}m$) is:

• A. 7.26
• B. 3.63
• C. 14.52
• D. 29.04

Answer 1

The correct option is A 7.26

We know that $K.E=\frac{1}{2}m{u}^2$

$⟹u^2=\frac{4.55\times {10}^{-25}}{0.5\times 9.108\times {10}^{-31}}$

$⟹u={10}^{3}m/s$

Now,

$\lambda =\frac{h}{mu}$

On substituting the values of h = 6.626$\times {10}^{-34}$Js and m = $9.1\times {10}^{-31}$ kg, we get

$\lambda =7.26\times {10}^{-7}m$